Just binged the last 9 episodes today. Similar to Season 1, it was very slow at parts, and then majorly picks up.
Stuff with side characters, not related to either Cassian, Mothma, Luthen, or Deidra/Cyril, I was basically skipping. Although I was trying to pay attention if any of it came to major relevance later, and honestly msot of it did not. I think any of the lesser arcs outside of those those characters can be almost entirely cut, outside of where they intersect with the main characters.
The act structure will be tricky, but this can definitely be made into ONE great film. Anymore than that would be stretching it IMO.